Adhesive sheet materials for use in general industry, packaging, and medicine/surgery are wellknown and highly developed. These materials are composed of a backing and a coating of pressure sensitive adhesive (PSA) which are selected so as to provide an appropriate balance of the desirable properties for adhesive sheet materials: adhesion and elasticity. In addition, such properties as peel strength and creep resistance are often considered. These properties of adhesive materials have been reviewed by Dahlquist in Interdisciplinary Science Review, 2, 2 (1977) and more recently in Adhesives Age, March, 1982, incorporated herein by reference.
Typically, adhesive sheet materials or tapes are designed with selected variations of the foregoing properties so that the sheet or tape will effectively adhere to the targeted surface. For example, a sheet or tape for adhering packages will exhibit high cohesion and adhesion but low stretchiness and elasticity. The peel strength for such a packaging tape will be low but the shear strength and creep resistance will be high.
A paper binding tape will generally exhibit high adhesion but practically no elasticity. It will have a relatively high shear strength. Its tack will be high so that low pressure will cause it to adhere.
A sheet or tape for use on living skin will exhibit moderate adhesion and moderate to high stretchiness and elasticity. The cohesive strength of such a sheet or tape should be high enough so that no PSA residue will remain on the skin when the tape is removed. This sheet or tape will also exhibit a high tack so that moderate pressure will cause adhesion.
The presence of a fluid between the sheet or tape and the surface to which it is to adhere will typically cause adhesion failure. Water and other nonadherent substances, such as oil, are well-known vexations to anyone trying to apply tape to skin. The physical barrier posed by the fluid prevents the PSA from binding to the surface. Since such fluid covered surfaces are a perennial problem when using adhesive sheets and tapes, much research has been devoted to the solution.
"Breathable" and "absorbent" adhesive tapes for combatting this problem are commercially available and have been extensively described in the patent literature. For example, Copeland in U.S. Pat. No. 3,121,021 describes a breathable surgical tape made of a nonwoven backing and microporous layer of PSA. The microporous PSA layer allows water vapor to pass through.
A different technique is described by Gander in U.S. Pat. No. 3,579,628. Gander discloses a dressing film in which the film-backing absorbs water vapor and the water acts as a plasticizer for the polymer composing the film. The film is self-adherent when wet.
Film absorption of water is also addressed by Potter in European Patent Application 0 091 800. Potter describes an adhesive surgical film in which the PSA is pattern coated onto the film. The film is water vapor absorptive.
Rawlings has further developed the absorptive reservoir concept in U.S. Pat. No. 5,010,883. Rawlings describes a multilayer adhesive coated sheet material in which the adhesive coated layer is perforated for transmission of liquid water. The surface layer is a continuous vapor transmissive film. Liquid water is transported into a reservoir region between the two layers and slowly evaporates as vapor from the surface layer.
These improvements in adhesive sheet materials or tapes, however, are designed to handle slight amounts of moisture. They cannot handle significant quantities of liquid water. In addition, the absorptive capacities of PSA's and backings typically used for such "absorbent" sheets and tapes limit the amount of moisture vapor that can be removed from the surface. Finally, the adherent ability of such sheets and tapes is poor when applied to wet surfaces. Consequently, at present, no adhesive sheet material or tape is available for use on extremely wet surfaces. In particular, no known adhesive sheet material or tape can effectively be used under water or upon a surface such as skin that has been thoroughly wetted with a stream of water. As a result, there is a need to develop an adhesive sheet material or tape which is suitable for use under extremely wet conditions. A further need exists for the development of such a sheet material or tape which will bind to an extremely wet surface such as skin covered with water or immersed in water.